1. Field of the Invention
This invention relates to data printers and has particular reference to printers for printing stacks of papers, paper forms or the like of varying thicknesses.
2. Description of the Prior Art
Printers of the above type have been employed heretofore and are generally of the impact type wherein type hammers or type bearing members are spring impelled against the paper to effect an imprint. In such cases, the thickness of the paper stack has little effect on the quality of the printing impression on the outermost paper or surface. In cases where interleafed carbon papers are required to provide multiple copies, it has been general practice to adjust the tension of the hammer impelling springs in accordance with such number of copies. That is, in those cases where a large number of superimposed copies are to be printed, the spring tension is increased. This is normally effected as an adjustment prior to the printing operation.
Although impact printers of the above type are generally satisfactory, they are obviously noisy in operation.
Squeeze type printers, which are inherently quieter than impact printers, have also been used heretofore. In such printer, a platen or a type of bearing member is forced, at a controlled rate of movement, against the paper to effect an imprint. Such printers must exert considerable pressure during imprinting operations and are generally operated by cams, toggles or levers which have a definite throw and therefore can not accomodate widely different thicknesses of paper stacks. Accordingly, the quality of impression varies considerably with the thickness of such paper stacks.
Accordingly, a principal object of the present invention is to provide a data printer of the squeeze type capable of accomodating various thicknesses of stacks of papers to be printed.
Another object is to provide a data printer of the above type which automatically adjusts the throw of the platen in accordance with the thickness of the paper stack to be printed.
A further object is to provide a data printer of the above type which is reliable and economically manufactured.